Many of the refineries in the United Kingdom came on stream in the late 1950s and early 1960s, reflecting the post-war demand for petroleum products as the economy recovered, road transport expanded and car ownership took off. Since that time, refineries have evolved to meet the growing demand for more complex and environmentally friendlier fuels, as well as the myriad by-products such as solvents and petrochemical feedstocks.

The result is that no two refineries are identical - although the common factors are similar crude distillation and upgrading units - each taking a slightly different route to a common goal of extracting maximum value from each barrel of crude oil processed.

Crude Oil

In its natural state, crude oil has little practical use, but by refining it we can end up with liquid petroleum gas (LPG), petrol, diesel, jet fuel, gas oil, heating oil and residues such as bitumen. Refining also provides the by-products or feedstocks for lubricants and, most importantly, for petrochemicals which are the basis for plastics, paints, adhesives, detergents, resins, solvents, synthetic fibres and rubber.

The type of crude oil processed - for example, lighter and 'sweeter' North Sea Brent blend or Arabian heavy - has an influence upon the mix of products a refinery produces. UK refineries process a range of crude oils, but those from the North Sea predominate (about 52% of the total). This helps refineries produce the high-quality, low sulphur road fuels that modern vehicles require to deliver low exhaust emissions.

Typically, a barrel of crude oil processed in the UK will yield: 30% petrol, 25% diesel, 13% gas oil, 9% jet fuel, 9% fuel oil (heavy residue for power generation), 4% LPG, 4% heating oil, 4% naphtha and 2% bitumen. A heavy crude oil will yield a much smaller proportion of petrol, diesel and kerosene, and the balance fuel oil residue which requires further processing to transform it into lighter more useful fuels.

Typical Refinery Processing Units

Refinery operations can be broken down into five main processes:

Distillation which separates crude oil into different refinery streams.

Conversion and reforming which improve the quality of these streams and adjusts the yields to meet market demand.

Desulphurisation which reduces the sulphur in the streams to the required level.

Blending of the refinery streams to produce the final products meeting current regulations and specifications.